Purification of petroleum phenols



Sept. '19, 195 0 J, sHMlDL 2,523,154

PURIFICATION OF PETROLEUM PHENOLS Filed Sept. 27, 1947 HIGH BOILING v 45Phenols Phenols 25 Petroleum i Solvent won" I 2 23 Va or P PHENOLSCONTAMINATED Flxed WITH ORGANIC SULPHUR 4L. Gases COMPOUNDS 43 42 35VACUUM TOWER 38 i i 39 i 34 l9 i Petroleum l Solvent 27 V l S Healer Oil44 i l VIB H Selllinq s n i Settling Ar I 12 I 6 30 no me Liquor ZoneZone 3| Zone Conloinmq v Phenols IS 28x,

Water Sulfuric Sulfuric Acids Acid Acid WWW, INVENTOR.

a phase which can be recovered:-

Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE PURIFICATION OFPETROLEUM PHENO LS Albert J. Shmidl, Houston, Tex-., assign'or, by

mesne assignments, to Standard Oil Develop- .ment Company, Elizabeth, N.J., a corporation of Delaware Application September 27, 1947, Serial-No.776,534

'4 Claims. (Cl.'26 0"--627-) 1 The presentihvention is related to thetreat ment; of petroleum hydrocarbons with aqueous alkaline solutions.More specifically, it is directed to recovery of phenolic materialswhich are, presentin the aqueous solutions used in the treatment ofpetroleum hydrocarbons. The invention is further directed to a' methodfor the production of. phenolic materials of improved quality.

It is well known that certain petroleum hydrocarbon mixtures containacidic'materials, such. as phenols and phenolic derivatives, and organicacids, which are objectionable if allowed to remainin the hydrocarbonmixture during its use. Substantial quantities of these acidic materialsare frequently present innatilral l troleums'; however, even greaterquantities are produced during certain processing stages of refiningsuch as in thermalcracking of selected. fractions. of

natural. petroleum for the manufacture of gaso' line, gas. oil,.and'other products. Ifthese acidic materials remain in the product, such.asfor example the gas oil, they result in corrosion of equipment duringthe, useof the, product and alsothey impart undesirableodors to'theproduct. The customary procedure for. removing acidic materials frompetroleum hydrocarbons includes treating the hydrocarbon containingthese materials with an aqueous alkaline solution, such as for example,sodium hydroxid or potassium hydroxide. The acidic bodies are convertedto their correspondingmetallic salts, sometimesreferred toias soaps, bythis treatment and are thus extracted from the petroleum' into theaqueous phase.

' It haslong been known that petroleum phenols could be separated fromthis alkaline extract for use as starting materials i in the manufactureof a number of va1i1ab1e roducts sucl'ias detergents, wetting agents andinhibitors of various types. The usuar procedure for'recovering thesephenolic: materials Chas been to neutralize an alkaline liquor derivedifrom the treatment of a petroleum. hydrocarbon mixturec'ontainingphenolsrwith aamineralacidi-to suchan extentath-at the: phenolicmaterials are. separated as an oil The disadvantages-of this, processfor, recovering phenolic materialsi are that :appreciable quantitiies ofundesirable' oils and: sulfun compounds are usually present:in-therecovered' phenols. It is" diflicult' to purify: thephenolsproduced" as the impurities usuallyboil in.the same range as the phenolsand chemical: treatment for their removal expensive For: some purposes?the: phenols; containing the above mentioned impurities maybe utilized;however, for other uses, the presence of these impurities renders thepetroleum phenols of inferior quality; For example, in themanufactureofphenol-formaldehyde resins the presenceof the oilymaterials, which are sometimes referred to as inert oils, causes theresultingresih to be tacky and poorly cured. Likewise; the presence ofsulfur compounds, which are usually mercaptans,. results in a productpossessingaj dis agreeable odor'and'is therefore undesirable. Phenolsderived from petroleum in the manner'described above are also used asantioxidants to retard the oxidation reaction which causes gum formationi'ngasoline exposed to air. In ad'die tion, they are employed in themanufacture of fungicides and insecticides, and the substitutedderivatives are frequently used in the manufac'-'- ture ofwettin agentsand detergents by alkyla tion with unsaturated compounds. It can beeasilyre'cog'nized that the presence of impurities, such as mercaptans,may be particularly ob'- jectionable where the phenolic material is usedto manufacture the products mentioned above;

It'is'the main object of this invention to pro;- vide a method forprocessing an aqueous alkaline solution containing. metallic salts ofphenolic materials in such a manner as to recover petroleum, phenols ofimproved quality. Other ob.- jects. will become apparent on reading thespecifi cation.

I'have now discovered that, by a combination of steps including. partialneutralization and ex:- traction with a petroleum solvent, a phenolicproduct can be produced from the waste alkaline liquor derived from thetreatment of petroleum hydrocarbons ,with aqueous alkaline solutionwhich is substantially free of mercaptans and which has reducedquantities of the undesirable inert oils. V

Theprincipal steps in the process: of the pres ent invention includeneutralizing aqueous alkaline solution containing the desired phenolicma,- terials," and then extractingthe solution with a petroleumsolventwhich has a greater aifinity for the undesirable constituents of themixture than for the desired phenolic product, andrfinally substantiallycompletely neutralizing the-solution;

Briefly, then, the invention comprises diluting an. aqueous alkalinesolution which hasbeen employed to treat petroleum hydrocarbons con.-taining phenolic material with water, followed by settling to-recover anaqueous phase, and. dis.-

carding an oil phase. The aqueous phase is" then treatedwith mineralacid in an amount sufiicient to liberate weakly acidic materials, suchas the more weakly acidic phenols, and sulfur compounds, such asmercaptans, but in an amount insufiicient to cause phase separation. Thepartially neutralized mixture is then extracted with a hydrocarbonsolvent and the rafiinate and extract phases separately recovered. Theextract phase is distilled for recovery of the hydrocarbon solvent and aphenolic product containing appreciable quantities of sulfur compounds.The aqueous phase is subjected to treatment with additional mineral acidin an amount sufficient to liberate the more acidic phenolic materialsand yet maintain in the alkaline solution the highly acidic aliphaticacids. ture separates into an aqueous phase and an oil phase, the oilphase being separated and distilled for the removal of water and therecovery of phenolic material of improved quality. The aqueous phasewhich contains highly acidic materials, such as aliphatic acids, may bediscarded or recovered if desired.

The invention will be more clearly understood from the followingdescription which is given in conjunction with the drawing in which thesingle figure is a schematic flow diagram of one mode of practicing theprocess of the present invention.

For purposes of description, it will be assumed that a petroleumhydrocarbon boiling in the range 1 of 420 to 620 F. containing phenolicbodies has been extracted with a solution of sodium hydroxide ofapproximately 35 to 40 Be. in an amount sufficient to neutralizeentirely the acidic materials present in the hydrocarbon mixture. y

The products of this treatment will be a purified hydrocarbon mixtureand an aqueous alkaline solution containing the oil soluble sodium saltsof the acidic materials formerly present in the petroleum hydrocarbons.This aqueous alkaline solution constitutes the charge stock for thepresent process.

Referring now to the drawing, numeral I des ignates a line by which theabove mentioned alkaline liquor is charged to settling zone l2. Thenumeral l3 designates a line by which water may be admitted to line Hfor dilution of the aqueous alkaline liquor prior to its injection intosettling zone l2. The alkaline liquor contains a small amount ofentrained emulsified oil from the treating stage and the added waterfacilitates the separation of this oil into a separate upper layer uponstanding. The amount of water added by way of line l3 will usually beapproximately one volume for each volume of phenolic soaps chargedthrough line however, smaller or larger quantities may be used asrequired to bring about optimum separation of the oil in settling zoneI2. The residence time in settling zone l2 will be sufficient to allowthe separation of the oil phase which rises to the top of the vessel andis withdrawn by way of line IA.

The aqueous phase is withdrawn from settling zone I2 by way of line |5which discharges into a second settling zone l6. A quantity of a mineralacid, such as sulfuric acid, is admitted to line by way of branch lineI! in an amount suificient to neutralize partially the alkaline liquorin line I5. It will usually be found desir able to employ sulfuric acidhaving a strength of approximately however, other concentrations fromabout 20% to about 80% may be satisfactorily employed. The totalquantity of acid employed in this step will usually be in the range of10% to of the theoretical equivalent for complete neutralization. Thepartially neutral- The latter mix-- 4 ized material flowing in line l5has mixed with it a quantity of a petroleum solvent which is admitted byway of branch line I8 and which may be either recycled as describedlater, or may be added from a source, not shown, by way of line IS. Themixture of partially neutralized aqueous alkaline liquor and petroleumsolvent in settling zone l6 separates by gravity into an upper extractphase and a lower aqueous or rafiinate phase.

The extract phase is discharged from zone l6 by line 28 to fractionatingtower 2| which may contain suitable internal equipment for intimatecontact between vapors and liquid and which is equipped with suitablemeans such as heating coil 22 for supplying heat for distillation. Thedistillate from fractionating tower 2! which consists primarily of thepetroleum solvent mentioned above leaves by way of line 23 and may bereturned to line 8 by way of line 24 fer recycling in the process byclosing valve 25 in line 45 and opening valve 26, or if desired it maybe discharged from the system by way of line 45, in which case Valve 25is open and valve 26 is closed. If the solvent is to be recycled, valve21 in line l9 remains closed except when addition of fresh solvent isrequired to compensate for losses from the system. In the event it isdesired only to employ fresh hydrocarbon solvent, valve 26 is closed andvalves 25 and 21 are open. The bottoms from tower 2! consist principallyof phenols and are withdrawn through line 41.

The partially neutralized aqueous raflinate phase leaving zone I6 by wayof line 28 has added to it by branch line 29 an additional quantity ofmineral acid, such as sulfuric acid, suiiicient to obtain a pH ofapproximately 9 in the solution. Under these conditions, the phenolicmaterials not liberated in the previous neutralization step areliberated and separated as an upper oil phase in zone 38 to which theneutralized railinate is admitted by line 3|. The upper phase whichseparates in zone 38 comprises a mixture of phenolic materials and isdischarged by line 32 which passes to zone 33 where the mixture isheated to a sufiicient extent to evaporate all of the water which iscarried in the stream. The heated stream flows by way of line 34 intozone 35 which is operated at a sufiiciently low pressure for the removalof substantially all of the water present in the stream as vapor whichis discharged by way of line 36. Zone 35 is not equipped with means foradditional heating; however, it may be equipped with suitable bafiles toprevent the entrainment of phenolic material with the water vaporleaving by way of line 36. The dehydrated oil is discharged from zone 35by way of line 37 to fractionating tower 38 which, similar tofractionating tower 2|, is equipped with suitable internal means forsecuring contact between liquid and vapor and with a means 39, such as aheating coil, for supplying heat for distillation.

It will usually be found desirable to operate tower 38 at reducedpressure and this is accomplished by use of suitable vacuum producingequipment such as steam ejector 40 connected to tower 38 by line 4|.Steam from the ejector together with non-condensible gases is dischargedto the atmosphere by way of line 42. The distillate from fractionatingtower 38 is discharged by way of line 43 and comprises the purifiedphenolic materials, while the bottoms of fractionating tower 38 isdischarged by way of line 44 and comprises a mixture of higher boilinphe- 2;"52851fl54 5 i 6 n'olic: materials; also containing. reducedamounts to facilitate the. separation of" entrained oil: par.- orssulfurcompounds;- l l ticles. Portions of the diluted phenolic soapslThei-aqueouslayer, separated" iir zorie130; c'omfrom the remainingaqueous alkaline solution ptriseslthe ali'phatic acidic material'sandmontamS were acidified with 10-, 20, 30, 4'0, 50, 60, and 70substantially no phenolic material. It isdis- 5 per cent ofthetheoretical acid requirements for oharged from zone 3-Ubyi way ofilin'exluand may complete neutralization in a first neutralization be discarded0r use d' -als the Cha gin mat'eri'all'in step.- The amount of acidrequiredfor total neuother: processes for the recovery ofitscompo'stralization was first determined by'titrating a nentst l l 3representative sample of the dilute phenolic soaps "W the p v o d cripion i eiven in'con l0 with sulfuric acid of approximately 30% HSOi j i nwi h re me of a pe r leum hvconcentration to the phenolphthaleinendoint.

d ob b e the range o to The sulfuric acidused in-these preliminaryparit"is tobe understood that hy roc rbon mi t tialneutralizationsteps-was also of approyimately bffahyldesired bo grangeand containingdesir 30% concentration. The homogeneous solution a bc' p o c compouunds may be Sim la y resulting from the preliminaryacidification was r e l ik wi i h s n m t one h then'extractedwith25volume per cent of isopenthe amount of sulfuric acid employed -pr tanebased on the dilute phenolic soaps; The limi a y p al idifi ation stepis in-the'ranee mixturethus-ronned was agitated to obtain good of 110%to 50% of the theoretical equiv ent fo contact and the hydrocarbon phaseallowedt'o complete neutralization. Although: it will usually -30separate'by gravity settling.

be found d sirabl to p at n t s ra th The hydrocarbon phase, containinghenolic r ne eiv n n t o be co s u d as' mit 't material and some sulfurcompounds, was then i o q n y being limited ly titan separated and theaqueous phase was removed amountsmall r h n' h r q to'oause ph andtreated with additional quantities of 30 per p r i n prior theadmissionof the-'hydrocent sulfuric acid such that the prior the" neu- C'am OH sov i Th8'q11a11tity 0f" yd -0 a 0 tralized solution was'approximately9.0. Under o v o b n y' tl in the e tract on stcp'will these conditions,there occurred a separation of recycling.

1151194113" 25 t0 um p Cent; based up n phenolic material asxan oilphase while the more t par d aqu us l qu r' m1 s tt n n acidic aliphaticacids remained in the aqueous however, larger qu8ihtitiesdnay be p y 30solution'by virtue of the slight residual alkalinity:satisfactoryresults having been obtained" with as Th mixture was anowe tseparate completely high as 5% of solvent. The quantity is and theoilphase was recovered. The recovered erned chiefly by the degree of"separation ob"- oil phase'was' then distilled under a subatmostanned andthe cost or recovering thesolventt for pheric pressure to '70 percent ditill te, leaving f 30 per cent of thematerial in the residue. Sulfur Theydrocarbon solvent emp y in the praodeterminations were then made on theOto 70 per time of this inv n i n ay be any petroleum hycent'distillateobtained. above by the bomb sulfur drocarbon of suitable boiling rangefor separation th analytical procedure for" t i t st romi h ph n ls bydisti11ation,.which is un fis given in. the 1946 edition of A. s. T.M..stand2- fected by treatment with sulfuric acid and which do a d nPetroleum Products-Committee D-2', is not reactive with the phenolicmaterials or pages 426-428. The amount of so-called inert othermaterials present in the solution being oilsvvas then determined bytreating a portion of r i Hydrocarbons Suitable f r his p rpo the 0" to70 per cent distillate with two'volum'es'oi are 'th'e paraflinichydrocarbonssuch as propane, 27Be'; caustic alkali, extracting themixture thus butane, pentane, hexane, heptane, or octane or obtainedwith petroleum ether, evaporating the mixtures of these. Aromaticsolvent may be emether from the extract and weighing the remain;-ployedin some cases; however, the paraffinictypes ing oil. wilrusuallybepreferred'; In the'recovery'of phe- The beneficial aspeotsof thetreating procedure nolio materials of the type usually found in gasdescribed above are illustrated by the following o it Will usually befounddesirable to usebudata which show the sulfur content and the inerttane, isopentane, or pentane as the hydrocarbon oil content of thefinished phenolic product, tosolvent since this material has the desiredsolugether with the percent of phenols, oils, and sulbility effect uponthe phenolic materials and is fur compounds removed by the hydrocarbonsoleasily recovered by simple distillation. vent extraction whenacidifying, in two steps, an

aqueous solution of phenolic soaps.

TABLE Fractional acidification of phenolic soap In order to demonstratethe advantages of the Preliminary acidification, per cent of theoreticalacid requirement added 10 20 30 40 5O 70 98 Per cent of phenols, oil,and sulfur compounds removed with isopentane Wa sh 5 6 6. 5 7 7 7 5 12.5 Per cent of theoretical acid requirement added to isopentane-washedsoap- 88 78 68 58 48 38 28 Phenols from Secondary AcidificationDistilled to 070% overhead phenols:

Bomb sulfur, per cent by wei ht 0.52 O. 32 0 24 0.11 0.18 0.23 O. 44Inert oil per cent by wei ht 3. O9 1. 71 1 80 1. 20 1.72 2.00 6. 98

1 Determined by extracting material insoluble in 2 volumes of 27 B.caustic. method of the present invention, a number of While the datashow that a total of 98% of the runs were conducted in which purifiedphenolic theoretical acid required for complete neutraliza' materialwas'recovered from a mixture of phetion was added in the twoneutralization steps, nolic soaps by the procedure of partialacidificathis is an approximate value as the actual amount tion andextraction in accordance with the inof acid employed was that amountrequired to vention. In conducting the runs, data from obtain a pH ofapproximately 9.0 in the solution which are shown in the followingtable, a conof the second neutralization step.

centrated aqueous alkaline solution obtained It will be observed fromthe data in the above from the treatment of a cracked petroleum hytablethat the quantity of sulfur and of inert oil drocarbon fraction boilingin the gas oil boiling in the finished phenolic material is increased asrange was diluted with an equal volume of water the quantity of acidused in the preliminary acidification step is increased beyond 50% ofthe theoretical requirement for total neutralization.

In the present specification and claims, the term phenolic material isused with the intent to cover hydroxy-aromatic materials such as phenol,cresol, xylenol, and other similar materials occurring in and derivedfrom petroleum hydrocarbons. By the term phenolic soaps is meant theproduct of reaction between the above mentioned phenolic materials andan alkali metal hydroxide.

The nature and objects of the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent is:

1. A process for recovering phenolic materials from an aqueous alkalineliquor containing them which comprises partially neutralizing thealkaline liquor with a quantity of a mineral acid in the range between10% to 50% of the theoretical acid requirement for completeneutralization of said alkaline liquor to form a first homogenoussolution, extracting said first solution by agitating same with ahydrocarbon solvent, settling said agitated solution, to form an extractphase and a raffinate phase, subjecting the raflinate to treatment withan additional amount of a mineral acid to form a second solution havinga pH of approximately 9, separating an oil phase from said secondsolution, and recovering phenolic material from the oil phase.

1 2. A method in accordance with claim 1 in which the hydrocarbonsolvent is a saturated paraiiin hydrocarbon.

3. A process for recovering phenolic materials from an aqueous alkalinesolution containing them and organic sulfur compounds which comprisesadding to the solution, sulfuric acid of a concentration in the range ofto 80 per cent H2SO4 in an amount between 10 and 50 per cent of thetheoretical requirement for complet neutralization to form a firstpartially neutralized solution, extracting said first solution with aparafiin hydrocarbon solvent to form an extract phase and a raffinatephase, separating the phases, distilling the extract phase andrecovering separately therefrom a fraction containing phenolic materialand organic sulfur compounds,

and a parafiinhydrocarbon fraction, adding to the raffinate sulfuricacid of 2G to 80 per cent H2804 concentration to form a second partiallyneutralized solution having a pH of approximately 9.0, causingsaidsecond solution to form an oil phase and an aqueous phase, separatingsaid oil and aqueous phases, distilling the oil phase to remove waterand to recover phenolic material containing reduced quantities oforganic sulfur compounds, and discarding the aqueous phase.

4. A process for recovering phenolic materials from an aqueous solutionof sodium hydroxide containing them and organic sulfur compounds whichcomprises adding to the solution sulfuric acid of a concentration in therange of 20 to 80 per cent H2804 in an amount between 10% and of thetheoretical requirement for complete neutralization to form a firstpartially neutralized solution, extracting said first solution with 25to '75 volume per cent of isopentane based on the aqueous alkalinesolution to form an extract phase and a raffinate phase, separating thephases, distilling the extract phase to recover separately a fractioncontaining phenolic material and organic sulfur compounds and anisopentane fraction, subjecting the rafiinate to treatment withsufficient sulfuric acid of 20 to per cent H2504 concentration to form asecond partially neutralized solution having a pH of approximately 9.0,causing said second solution to form an oil phase and an aqueous phase,separating said oil and aqueous phases, distilling the oil phase toremove water and to recover phenolic material, and discarding theaqueous phase.

ALBERT J. SHMIDL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number 7 Name Date 2,391,128 Cauley et a1 Dec. 18,1945 FOREIGN PATENTS Number Country Date 386,977 Great Britain Jan. 18,1933

1. A PROCESS FOR RECOVERING PHENOLIC MATERIALS FROM AN AQUEOUS ALKALINELIQUOR CONTAINING THEM WHICH COMPRISES PARTIALLY NEUTRALIZING THEALKALINE LIQUOR WITH A QUANTITY OF A MINERAL ACID IN THE RANGE BETWEEN10% TO 50% OF THE THEORETICAL ACID REQUIREMENT FOR COMPLETENEUTRALIZATION OF SAID ALKALINE LIQUOR TO FORM A FIRST HOMOGENOUSSOLUTION, EXTRACTING SAID FIRST SOLUTION BY AGITATING SAME WIT'' AHYDROCARBON SOLVENT, SETTLING SAID AGITATED SOLUTION, TO FORM AN EXTRACTPHASE AND A RAFFINATE PHASE, SUBJECTING THE REAFFINATE TO TREATMENT WITHAN ADDITIONAL AMOUNT OF A MINERAL ACID TO FORM A SECOND SOLUTION HAVINGA PH OF APPROXIMATELY 9, SEPARATING AN OIL PHASE FROM SAID SECONDSOLUTION, AND RECOVERING PHENOLIC MATERIAL FROM THE OIL PHASE.